土壤微量元素空间分布特征及质量评价

The Spatial Distribution of Soil Trace Element in Surface Soil and Quality Evaluation

【目的】以汉江中上游典型小流域余姐河流域为研究区,网格状采集土壤样品,分析土壤中微量元素有效Cu(Cu)、有效Fe(Fe)和有效Zn(Zn)等指标,旨在为研究区合理规划利用水土资源提供有利的科学依据。【方法】利用地统计学方法和模糊数学综合评价法研究土壤微量元素空间分布特征并对研究区土壤微量元素质量进行评价。【结果】研究区土壤Zn含量服从正态分布,其余指标均服从对数正态分布。土壤微量元素含量随着土层深度的增加而减小,利用GIS对研究区耕层土壤微量元素进行Kriging最优内插,发现土壤微量元素空间分布和土地利用类型相关,林地土壤Zn含量最高。通过模糊数学综合评价发现研究区土壤微量元素综合评价结果属于三级标准,总体来说,余姐河流域土壤中微量元素含量较高。土壤中有效Fe、有效Cu、有效Zn的指数均大于1,其中有效Zn的最大,为4.96。【结论】余姐河流域土壤微量元素在表层富集,且在不同的区域存在本底差异,极差最小的是Zn;土壤微量元素均属于中等变异,且微量元素的变幅在8~33倍。土壤有效Cu、有效Zn含量丰富,而土壤有效Fe含量为中等水平,土壤Cu和Fe具有强烈的空间自相关性,而Zn的空间相关性较弱。土壤Cu含量高值区主要以草地、梯地和坡耕地为主;Zn的高值区主要出现在草地和林地。研究区土壤中微量元素含量均超过元素背景值,其中有效Zn含量超出背景值程度最高。

【Objective】Taking the Yujie River Basin,a typical small watershed in the middle and upper reaches of the Hanjiang River,as the research area,the soil samples were collected in the grid,and the effective copper(Cu),effective iron(Fe)and effective zinc(Zn)in the soil were analyzed.Provide a favorable scientific basis for the rational planning and utilization of water and soil resources in the study area.【Method】The geostatistical method and fuzzy mathematics comprehensive evaluation method were used to study the spatial distribution characteristics of soil trace elements and evaluate the soil trace element quality in the study area.【Result】The soil Zn content follows a normal distribution,and the other indicators are subject to a lognormal distribution in the study area.The soil trace elements content decreased with the increase of soil depth.The spatial distribution of soil trace elements was related to the land use type and the soil Zn content was the highest in forest land.The comprehensive evaluation results shown that soil trace elements belong to the third-level standard in the study area.In general,the trace elements content is higher on Yujie River Basin.The available iron,available copper and available zinc index is greater than 1,and the maximum value is effective zinc,was 4.96.【Conclusion】The trace elements are enriched in the surface soil layer,and there are differences background in different regions.The trace elements are moderately variable,and the variation of trace elements is between 8 and 33 times.Soil available copper and available zinc are abundant,while soil available iron content is moderate.Soil Cu and Fe have strong spatial autocorrelation,while Zn was weak.The high value of soil Cu content is mainly grassland,terrace and sloping farmland;the high value area of Zn is mainly in grassland and woodland.The content of trace elements exceeded the background value in the study area,and especially the effective zinc content.